Ball-bearing glides used in connection with drawers and other accessories are encumbered by a number of shortcomings, many of which can result in premature product failure. One such shortcoming involves glide alignment. Ball-bearing glides are difficult for ordinary consumers to install properly and often require professional installation which is not practical for a consumer product. Even when installed skillfully, the glides are usually out of exact alignment in some direction. Humidity changes and other external factors can cause misalignment or exacerbate already existing misalignment of ball-bearing glides. If an accessory such as a drawer is installed onto glides that are not exactly aligned in all directions, the drawer will not operate properly due to the glides binding.
Ball-bearing drawer glides are sometimes installed with the glides oriented horizontally. Because of the horizontal orientation, there is little structural resistance to vertical deflection and the glides bend when the accessory is extended to the open position, particularly if under heavy loads. Once the glides become bent, the accessory will inevitably bind thereafter.
Ball-bearing glides have in some applications been installed in a vertical configuration. Unfortunately, just installing the glides in a vertical arrangement does not by itself solve the binding problem. While vertically oriented glides tend to suffer less deflection than horizontally mounted glides, even glides that are installed in a vertical orientation are susceptible to binding for the reasons previously given. If one or more of the fasteners used to fasten the glides to the accessory are tighter than others or installed at an angle or an imprecise location, the fasteners cause misalignment of the glides. Again, even a small amount of bending, skewing or other misalignment of the glides creates binding.
Ball-bearing glides with full extension, even when professionally installed in a rigid manner, experience a high rate of product failure. When an accessory equipped with a full extension glide is fully or nearly fully extended, the leverage exerted on the glides by the fully extended weight can create bending of the glides or even cause detachment of the fasteners attaching the glides to the cabinet.